Omentin-1, a novel adipokine, which is selectively expressed in visceral adipose tissue, participates in a variety of physiological processes, such as insulin action, inflammatory and cardiovascular function. The association of high serum/plasma omentin-1 level and colorectal cancer (CRC) has been reported. However, the molecular mechanism between omentin-1 and the onset of CRC is unclear. We explored the influence of omentin-1 on the human colon adenocarcinoma cell line, SW480 cell and the signal pathway involved in this study. Omentin-1 promoted human SW480 cell proliferation in a dose-dependent manner as determined by a methyl thiazoleterazolium (MTT) assay, and had no effect on human SW480 cell apoptosis evaluated by annexin V-FITC and PI double staining. Western blot analysis revealed that omentin-1 induced activation of Akt (phosphatidylinositol-3 kinase downstream effector) and such effect was impeded by transfection of human SW480 cells with Akt-siRNA. Furthermore, LY294002 (a selective PI3K inhibitor) and HIMO (a selective Akt inhibitor) abolished the omentin-1-induced human SW480 cell proliferation. These findings indicate that omentin-1 induces human SW480 cell proliferation via PI3K/Akt signaling pathway and suggest that CRC cell is a direct target of omentin-1.
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